Exam 3 Flashcards
(107 cards)
1
Q
What are the two circuits of the cardiovascular system?
A
- Pulmonary loop: carries oxygen-poor blood to the lungs and back to the heart.
- Systemic loop: carries oxygen-rich blood from the heart to the rest of the body.
2
Q
What are the components of blood?
A
- Formed elements: white blood cells, red blood cells, platelets.
- Buffy coat: white blood cells and platelets.
- Plasma: water containing proteins and other substances.
3
Q
Define hematocrit.
A
The proportion of blood volume that is occupied by red blood cells.
4
Q
What is anemia?
A
A condition characterized by lower than normal hematocrit.
5
Q
What is polycythemia?
A
A condition characterized by elevated hematocrit.
6
Q
What is the typical hematocrit range for females?
A
37-47%.
7
Q
What is the typical hematocrit range for males?
A
42-52%.
8
Q
What is the primary function of red blood cells?
A
Transport oxygen and carbon dioxide.
9
Q
What shape do red blood cells (erythrocytes) have?
A
Biconcave disk.
10
Q
What is erythropoietin?
A
A hormone that stimulates red blood cell production.
11
Q
How does erythropoietin increase hematocrit?
A
It stimulates the division and formation of more myeloid cells in the bone marrow, leading to increased RBCs.
12
Q
What is the function of the pericardium?
A
It allows the heart to move easily within the chest cavity.
13
Q
What are the major components of the heart’s anatomy?
A
- Chambers: right atrium, right ventricle, left atrium, left ventricle.
- Major vessels: SVC, IVC, pulmonary arteries, pulmonary veins, aorta.
- Valves: tricuspid, bicuspid, pulmonary, aortic.
14
Q
What are the characteristics of cardiac muscle?
A
Striated, contains intercalated discs, and has gap junctions for direct depolarization.
15
Q
What is the role of the sympathetic nervous system in heart rate control?
A
Releases norepinephrine and epinephrine, increasing heart rate and force of contraction.
16
Q
What is the role of the parasympathetic nervous system in heart rate control?
A
Releases acetylcholine, decreasing heart rate.
17
Q
What is the function of the SA node?
A
It initiates the electrical impulse and acts as the heart’s pacemaker.
18
Q
Where is the AV node located?
A
In the lower part of the right atrium near the interatrial septum.
19
Q
What occurs during the excitation of the heart?
A
1) SA node creates excitation signal. 2) Signal spreads across atria causing contraction. 3) Signal delayed at AV node. 4) Signal travels down the Bundle of His and branches. 5) Purkinje fibers spread impulses through ventricles.
20
Q
How does cardiac action potential differ from action potentials in neurons?
A
Cardiac action potentials have a long plateau phase due to Ca2+ entry.
21
Q
What is the significance of the long refractory period in cardiac muscle?
A
It prevents tetanus and allows time for ventricles to fill with blood.
22
Q
What are pacemaker potentials?
A
Special ion channels in pacemaker cells that allow spontaneous drift towards threshold.
23
Q
What does the P wave on an ECG represent?
A
Atrial depolarization.
24
Q
What does the QRS complex on an ECG represent?
A
Depolarization of the ventricles.
25
What does the T wave on an ECG represent?
Ventricular repolarization.
26
What causes the dicrotic notch in aortic pressure?
Closure of the aortic valve and elastic recoil of the aortic wall.
27
What is cardiac output?
The volume of blood pumped per minute by each ventricle of the heart.
28
Define stroke volume.
The amount of blood ejected from the heart in one contraction.
29
What is the equation for cardiac output?
CO = HR x SV.
30
What is the Frank-Starling mechanism?
It describes the relationship between stroke volume and end-diastolic volume (EDV).
31
What is ejection fraction?
Percentage of blood that leaves the heart each time it contracts, calculated as EF = SV/EDV.
32
What is afterload?
The pressure the heart must overcome to eject blood during ventricular contraction.
33
What causes the heart sounds 'lub' and 'dup'?
Lub: closure of AV valves at the start of systole. Dup: closure of semilunar valves at the start of diastole.
34
What is the physiological significance of the dicrotic notch?
It indicates the closure of the aortic valve.
35
What is the role of beta receptors in cardiac contractility?
They increase contractility by promoting calcium release in cardiac muscle.
36
What is the typical heart rate at rest?
70 bpm, influenced by parasympathetic tone.
37
What happens to stroke volume during sympathetic stimulation?
Stroke volume increases due to enhanced contractility.
38
Define afterload
The amount of pressure that the heart needs to exert to eject during ventricular contraction. Decreases SV.
39
What is the significance of afterload in hypertension and heart failure?
Heart must work harder to push against increased arterial pressure, reducing SV.
40
Describe the structure of arteries and their function in blood flow regulation.
Arteries have muscular walls that withstand pressure and contract/relax to regulate blood flow.
41
List the types of blood vessels in order from the aorta to the vena cava.
* Aorta
* Large arteries
* Arterioles
* Capillaries
* Venules
* Large veins
* SVC/IVC
42
Define arterial compliance and its relationship with pulse pressure.
Compliance preserves blood pressure during diastole; elevated arterial pressure increases pulse pressure for a given stroke volume.
43
What is the formula for calculating pulse pressure?
Systolic - Diastolic = Pulse Pressure.
44
What is mean arterial pressure (MAP)?
Average pressure over the entire cardiac cycle; closer to diastole due to longer duration spent in diastole.
45
How does blood flow regulate locally based on tissue conditions?
Blood flow is proportional to pressure difference and inversely proportional to resistance.
46
What factors can contribute to vascular resistance?
* Blood viscosity
* Total blood vessel length
* Blood vessel radius
47
How does the radius of arterioles affect blood flow?
Decreased radius leads to decreased flow rate; small changes in radius have a large effect on blood flow.
48
What is autoregulation in blood flow?
Local control mechanism where increased metabolic activity leads to arteriole dilation and increased blood flow.
49
List some vasodilators that affect blood flow.
* K+
* H+
* CO2
* O2
50
List some vasoconstrictors that affect blood flow.
* Endothelins
* Leukocytes
* Prostaglandins
51
What role do alpha adrenergic receptors play in vascular smooth muscle?
Norepinephrine causes vasoconstriction by acting on alpha adrenergic receptors.
52
What is the function of beta2 adrenergic receptors?
Cause vasodilation in skeletal muscle arterioles, counteracting vasoconstriction effects of alpha receptors.
53
Describe the structure of capillaries.
Walls are one cell thick surrounded by a basement membrane; allow water and some molecules to cross.
54
Why is blood flow slower in capillaries?
Slower blood flow allows for better gas exchange due to a large cross-sectional area.
55
What is the blood-brain barrier?
Capillaries in the brain have tight junctions, limiting permeability and protecting brain tissue.
56
Define the four Starling forces affecting capillary filtration.
* Pc: capillary hydrostatic pressure
* Pif: interstitial fluid hydrostatic pressure
* Πc: osmotic force due to plasma protein concentration
* Πif: osmotic force due to interstitial fluid protein concentration
57
What happens when plasma protein levels are low?
Decreased absorption leads to more filtration into interstitial fluid, potentially causing edema.
58
What is the function of the lymphatic system?
Drains excess fluid from tissues, maintaining fluid balance.
59
How do veins function as a reservoir for blood?
Veins contain ~60% of blood at rest; constriction increases venous return.
60
How do valves and skeletal muscle contraction promote venous blood flow?
Skeletal muscle pump and one-way valves assist venous flow, preventing backflow.
61
Explain the Frank-Starling mechanism.
Greater filling increases stretch and contraction, leading to increased stroke volume.
62
Define mean arterial pressure (MAP), cardiac output (CO), and total peripheral resistance (TPR).
MAP = CO x TPR; CO = product of HR and SV.
63
Where are baroreceptors located?
* Carotid sinus
* Aortic arch
64
What happens when arterial pressure increases?
Baroreceptors increase firing, leading to decreased sympathetic outflow and decreased TPR.
65
What is the role of the vagus nerve in blood pressure regulation?
Increases parasympathetic outflow to decrease heart rate and cardiac output.
66
What occurs when blood pressure decreases?
Decreased baroreceptor firing increases sympathetic outflow to heart and vessels.
67
What is hemostasis?
The process of stopping blood loss involving platelet plug formation and coagulation.
68
Describe the steps in platelet plug formation.
Platelets adhere to collagen, become activated, release mediators, aggregate, and form a plug.
69
List important substances involved in platelet plug formation.
* ADP
* Thromboxane A2
70
What is the coagulation cascade?
Involves tissue factor, factor Xa, thrombin, and factor XIII in clot formation.
71
What are the key substances involved in initiating or signaling during platelet plug formation?
* ADP
* Thromboxane A2
## Footnote
ADP and thromboxane A2 cause further platelet activation and trigger vasoconstriction, with aspirin inhibiting cyclooxygenase which makes TXA2.
72
What is the role of tissue factor in the coagulation cascade?
Primary cellular initiator of blood coagulation
## Footnote
Tissue factor activates the coagulation cascade leading to clot formation.
73
What does factor Xa do in the coagulation cascade?
Generates thrombin
## Footnote
Factor Xa is crucial for converting prothrombin to thrombin.
74
What is the function of thrombin in the coagulation cascade?
* Converts fibrinogen to fibrin
* Activates Factor XIII
* Activates upstream factors and platelets in a positive feedback manner
## Footnote
Thrombin stabilizes the clot by forming a meshwork with fibrin.
75
What is the role of factor XIII in the coagulation cascade?
Makes covalent bonds between fibrin molecules
## Footnote
This crosslinking is essential for forming a stable clot.
76
How do intrinsic and extrinsic pathways differ in the coagulation cascade?
* Intrinsic pathway: everything in the blood, usually triggered by thrombin
* Extrinsic pathway: requires tissue factor from cells below the endothelium
## Footnote
The extrinsic pathway typically starts the coagulation cascade.
77
How is the formation of the platelet plug linked to the coagulation cascade?
Platelet activation and aggregation initiate the coagulation cascade, while thrombin generated reinforces the platelet plug with fibrin strands.
## Footnote
The platelet plug provides an initial seal, and the coagulation cascade stabilizes it.
78
What is the source and function of prostacyclin and nitric oxide in the vascular system?
* Source: healthy endothelial cells
* Function: Limit platelet plug formation
## Footnote
Prostacyclin (PGI2) and nitric oxide prevent excess clot formation.
79
What is the function of protein C in coagulation?
Inactivates clotting factors Va and VIIIa
## Footnote
This is an anti-coagulant mechanism activated by thrombin.
80
What role does heparin play in coagulation?
Binds and activates antithrombin, inhibiting thrombin and Factor Xa.
## Footnote
Heparin is produced by endothelial cells.
81
What is fibrinolysis?
The dissolving of a stable clot
## Footnote
Plasma enzymes break down fibrin, with tissue plasminogen activator converting plasminogen to plasmin.
82
List essential substances for clotting.
* Ca2+
* Vitamin K
## Footnote
Ca2+ is needed for platelets and clotting factors, while Vitamin K is required to produce certain clotting factors.
83
What are the four processes involved in respiration?
* Ventilation
* Gas transport
* Internal respiration
* External respiration
## Footnote
These processes supply tissues with oxygen and dispose of carbon dioxide.
84
What distinguishes the conducting zone from the respiratory zone in the airways?
* Conducting zone: trachea to terminal bronchioles, for air movement
* Respiratory zone: gas exchange occurs, usually at alveoli
## Footnote
The conducting zone provides a pathway for airflow while the respiratory zone is where gas exchange takes place.
85
How does negative intrapleural pressure prevent lung collapse?
Acts as a suction to keep lungs inflated
## Footnote
If intrapleural pressure equals alveolar pressure, a pneumothorax can occur.
86
What is the significance of transpulmonary pressure?
Difference between alveolar pressure and intrapleural pressure
## Footnote
Normally, intrapleural pressure is less than alveolar pressure, preventing lung collapse.
87
Describe the stages of ventilation.
* Ventilation: air exchange
* Exchange of O2 and CO2 in lungs
* Transport of gases through circulation
* Exchange in tissue capillaries
* Cellular utilization of O2
## Footnote
These stages outline the complete process of respiration.
88
What is the role of surfactant in lung compliance?
Reduces cohesive forces between water molecules, lowering surface tension
## Footnote
Surfactant increases lung compliance, making it easier to expand the lungs.
89
Define tidal volume.
Amount of air inhaled or exhaled in one breath
## Footnote
Tidal volume represents a normal breath.
90
What is the difference between minute ventilation and alveolar ventilation?
* Minute ventilation: total air moved per minute
* Alveolar ventilation: fresh air entering alveoli per minute
## Footnote
Alveolar ventilation accounts for dead space in the airways.
91
Why is rapid, shallow breathing inefficient for oxygenating blood?
Moves air only in the conduction zone, not reaching alveoli
## Footnote
This limits the surface area available for gas exchange.
92
What is partial pressure?
Measure of concentration of individual components in a gas mixture
## Footnote
Calculated as PP = % of composition of air * total pressure.
93
How does the body attempt to match ventilation and perfusion?
By diverting blood flow and airflow away from areas of disease to healthy regions
## Footnote
This minimizes ventilation-perfusion inequality.
94
What is the relationship between PO2 and hemoglobin saturation?
As PO2 decreases, hemoglobin saturation falls rapidly
## Footnote
Saturation is determined by PO2, with a sigmoidal curve due to cooperative binding.
95
What can shift the hemoglobin saturation curve?
* pH
* Temperature
* 2,3-DPG
## Footnote
Increased levels of these factors make unloading of O2 easier.
96
List the ways CO2 is transported in blood.
* Converted to carbonic acid (~60%)
* Bound to hemoglobin (~30%)
* Dissolved in plasma (~10%)
## Footnote
These methods are crucial for CO2 transport and regulation of blood pH.
97
What reaction converts CO2 to carbonic acid?
H2O + CO2 <-> H2CO3 <-> H+ + HCO3-
## Footnote
Carbonic anhydrase catalyzes this reaction, helping buffer blood pH.
98
How do chemoreceptors regulate respiration?
Respond to changes in arterial blood, mainly PCO2 levels
## Footnote
They stimulate ventilation adjustments based on CO2 levels.
99
What do chemoreceptors respond to in the brain extracellular fluid?
Changes in PCO2 and proton concentration
## Footnote
Chemoreceptors are sensitive to the levels of carbon dioxide and hydrogen ions, which influence respiratory activity.
100
What triggers an increase in ventilation?
Changes in O2 and CO2 levels
## Footnote
The respiratory system responds to variations in oxygen and carbon dioxide to regulate breathing.
101
What happens when arterial PO2 decreases?
Increase in firing of peripheral chemoreceptors
## Footnote
This firing leads to a chain reaction that ultimately increases ventilation.
102
What is the sequence of events following a decrease in arterial PO2?
Peripheral chemoreceptors > medullary inspiratory neurons > diaphragm and inspiratory intercostals contraction
## Footnote
This sequence stimulates breathing to increase oxygen intake.
103
What effect does an increase in non-CO2 acids have on ventilation?
Increase in arterial [H+] and subsequent increase in ventilation
## Footnote
The increase in hydrogen ion concentration stimulates chemoreceptors, enhancing respiratory activity.
104
How does increased arterial PCO2 affect ventilation?
Increases brain extracellular fluid PCO2 and [H+]
## Footnote
Higher levels of carbon dioxide in the blood lead to increased acidity in the brain's extracellular fluid.
105
What is the result of increased firing of central chemoreceptors?
Increase in firing of medullary inspiratory neurons
## Footnote
Central chemoreceptors play a crucial role in regulating the respiratory response to carbon dioxide levels.
106
Fill in the blank: An increase in _______ leads to increased ventilation due to enhanced diaphragm and intercostal muscle contractions.
[PCO2]
## Footnote
Elevated carbon dioxide levels are a primary driver for increasing respiratory rate and depth.
107
True or False: Increased arterial PCO2 does not affect ventilation.
False
## Footnote
Increased arterial PCO2 is a significant stimulus for enhancing ventilation.
